With the improvement of people's living standards, people get satisfaction in material life, and also gradually begin to pursue leisure life, and with the rapid development of the Internet and the popularization of smartphones, people like to share themselves or things around themselves, such as travel experiences and clothes matching, on the Internet in forms such as videos, pictures or files. Therefore, to cater to people's life requirements, various types of social software that can help people perform text, voice, or video communication with friends around anytime and anywhere are derived.
For example, currently, some audio and video live stream projects (such as makeup teaching live stream and clothes matching live stream) are increasingly growing on the Internet. Therefore, these live stream platforms may provide skin care and clothes matching skills for women who care about beauty. However, in many live stream projects, a host of a live stream room can only interact with viewers in superficial manners such as the viewer sending bullet screen information or giving gifts. As a result, a large quantity of viewers in this manner only act as a spectator, and cannot fully arouse interactions between the host and many viewers, and when more bullet screen information are given, text information sent by viewers has a relatively single display effect, and therefore, cannot necessarily be noticed by the host.
Therefore, to fulfill the screen display effect, and increase interactions between the host and the viewers, may be designed an interaction that allows viewers to spray a pigment to the host, that is, the host is required to erase the pigment sprayed by the viewers by simulating an eraser with fingers. A figure formed by finger during sliding is an irregular figure. If the area the ratio of the part is calculated according to an existing technical method, a current sprayed pigment figure needs to be segmented into approximately regular figure, and then a complex calculation formula is used to calculate the area of each section. The calculation is huge, and calculation results for irregular images have relatively large errors. Especially, when an irregular figure are relatively complex, for example, when the figures have overlaps, repeated calculations may be needed, so that the area ratio of the irregular figure cannot be accurately calculated, and therefore, the original interface cannot be restored to.